1. Field of the Invention
This invention relates to the treatment of untextured protein materials to form a product possessing the fibrous texture and mouth feel properties of animal meat.
2. Description of the Prior Art
The food industry has spent much effort over a span of many years and has expended large sums of money in an attempt to utilize non-meat proteins, such as those derived from vegetables, as additives to or substitutes for animal meat products. It long has been recognized that the ever-increasing worldwide food shortage could be in material part obviated if only such relatively inexpensive materials could be converted into products so closely approximating the naturally occurring food material that public acceptance would be achieved. One of the major roadblocks encountered by the industry has been the inability to impart the natural and accustomed chewy, fibrous texture to vegetable protein materials. Animal meat products inherently possess a texture giving them a definite "mouth feel" which is clearly recognized and strongly preferred. Vegetable proteins in their natural state generally take the form of amorphous powders which, despite their unquestioned nutritive value, possess mouth feel characteristics wholly unacceptable to the consumer as a meat substitute. Moreover, vegetable proteins normally are characterized by objectionable "beany" flavors which the industry has been unable to remove or mask.
In recent years a number of processes and apparatus have been developed for treating vegetable protein material to produce a bland texturized product. None of these processes, however, has achieved any substantive measure of commercial success.
The first generation of these prior art techniques involved the wet spinning process disclosed in Boyer, U.S. Pat. No. 2,730,447. This process produces a fibrous product by extruding a plurality of fine streams of an aqueous solution of protein into a chemical coagulating bath. The protein coagulates into fine fibers which are collected together and treated to form an edible textured protein product. The wet spinning process suffers from a number of drawbacks in addition to its general failure to produce an adequately textured product as discussed above. The equipment employed to perform this process is extremely sophisticated for the food industry and represents a very high initial cost problem. Adding further to the economic infeasibility of the product produced by the wet spinning process is the expensive starting materials which must be employed. Moreover, product uniformity is difficult to achieve due to the general complexity of the process and the numerous parameter control problems presented.
The second generation technique advanced in this area is the extrusion cooking process disclosed in Atkinson, U.S. Pat. No. 3,488,770, in which a protein mass is physically worked at an elevated temperature and thereafter extruded at an elevated temperature and pressure through an orifice into a medium of lower pressure and temperature. This process also suffers from high equipment costs. In addition, the product produced by extrusion cooking has a very low density which swells up in water to give a "spongy" texture. Moreover, the product contains objectionable flavor notes in addition to the "beany" flavor originally present in the starting materials which are apparently imparted to the product by the processing steps.
The third generation of development in the protein texturization involves the use of steam as the texturizing medium. Exemplary of this approach are Strommer, U.S. Pat. Nos. 3,754,926 and 3,863,019 which treat either finely divided protein particles or slurries with steam and Heusdens U.S. Pat. No. Re. 28,091 which employs a steam treatment of a protein slurry following complex hydration steps. Products produced by these processes also possess the general problems of poor texture and flavor discussed above. In addition, the product has low density problems similar to the second generation extrusion cooked products in that on hydration they tend to be very soft. The product is also extremely friable.
Other attempted solutions by the art include the cooking and shaping of a protein dough disclosed in McAnelly, U.S. Pat. No. 3,142,571, and the heat coagulation of undenatured protein disclosed in Rusoff, U.S. Pat. No. Re. 27,790.
Notwithstanding the veritable plethora of prior art attempts to satisfactorily texturize vegetable proteins--no one to data has made any really substantial progress toward the desired goal. The present absence from the market of any commercially accepted consumer products based on vegetable protein demonstrates clearly that the problems involved simply have not been solved. Indeed, those meat analog products which have found their way to the supermarket shelves generally have been met with little or no consumer acceptance and have generally been withdrawn. Especially in the United States, where consumer preferences rather than nutritional values often dictate the fate of food products, a successful texturized vegetable protein material simply must possess taste and mouth feel characteristics similar to natural meat. In addition, the prior art processes generally have employed such complex apparatus and procedures that initial equipment and operating costs have made protein analog products economically unattractive to manufacturers, despite the relatively inexpensive nature of the raw product.
Given the ever-increasing fears of worldwide famine and the diminishing availability of animal meat protein products, it is clear that an inexpensive, consumer-acceptable, high protein food product based on texturized proteins is urgently needed.